The present invention relates to a mechanical chucking device especially suitable for use in a testing apparatus but not limited to such use. Two opposing clamping members for clamping test samples are slidably arranged on a base plate.
Many types of mechanical chucking devices for clamping samples in testing machines are known. For example, wedge chucks and chucks with two clamping plates or clamping members are known wherein the plates or members are drawn toward each other by screw means, whereby the sample is clamped between both clamping members or plates. The clamping plates in this type of chucking device are attached to a base plate by means of flexible straps or bars. The base plate itself is attached to the chuck head of the testing device, for example, with threaded bolts. Since the distance between the two clamping plates is practically constant due to the strap connection, intermediate plates or spacers must be used for samples of varying thickness. Hence, such testing machines are used especially for samples with fixed dimensions. It is not possible to continuously vary the sample dimensions, in other words, sample dimensions can be changed only in fixed increments.
In another known chucking device, the clamping members for clamping the sample are slidably arranged on the base plate and secured to the base plate, for example, by bolts which are guided in slots in the base plate. The sample dimensions may thus be continuously varied, however, the clamping members must be disconnected from the base plate and adjusted anew, when clamping a sample. This operation is involved and time consuming. In addition, special care must be taken if a concentric clamping and an exactly concentric power application to the test sample is to be guaranteed.